Machines, for example motor graders, are commonly used in earth leveling applications such as road maintenance or surface contouring. Motor graders typically have a steerable front frame and a driven rear frame connected to the front frame by an articulation joint. The front frame supports a movable drawbar-circle-moldboard (DCM) that holds a work implement used to perform the leveling operations. The DCM is suspended from a main beam of the front frame and has a yoke extending forward toward and pivotally connected to the front frame. Movement of the DCM relative to the front frame results in a corresponding movement of the work implement.
The work implement, typically a blade, is connected to a circle member of the DCM. The circle member is positioned relative to the yoke by way of shoes that allow relative rotation between the circle member and the yoke, but inhibit relative translation. During operation, the blade is exposed to significant forces and vibrations and, to reduce wear of the circle member and the yoke caused by operation, wear inserts made of a relatively softer sacrificial material are located between the shoes and the circle member and between the circle member and the yoke.
Over time, the softer material of the wear inserts erodes under normal conditions, and a clearance and relative movement between the shoes and the circle member and/or between the circle member and the yoke increases. This clearance and movement, if left unchecked, could result in improper positioning and/or orienting of the blade. An inaccurately positioned or oriented blade may not adequately perform an intended leveling operation.
In order to maintain desired DCM clearances, the wear inserts must be periodically adjusted and/or replaced. In some machines, maintenance of the wear inserts requires that the entire circle member and the shoes be completely removed from a bottom side of the yoke so that new wear strips and shims can be positioned between the circle member and the yoke. Although sufficient for some situations, this access to the wear inserts and performance of the associated adjustments can be difficult and require extensive time and labor.
One arrangement that allows access to and adjustment of the wear inserts with reduced time and labor is disclosed in U.S. Pat. No. 5,720,353 (the '353 patent) issued to Wilkening on Feb. 24, 1998. Specifically, the '353 patent discloses a yoke having a passageway extending therethrough, and a circle member movable relative to the yoke. The '353 patent also discloses a wear strip positioned within the passageway and located in contact with the circle member, and a shim positioned within the passageway and in contact with the wear strip. A holder is secured to a top surface of the yoke opposite the circle member to hold the shim and wear strip in place. After an operational period of time, when the wear strip has eroded by a significant amount, the holder is removed so as to expose the passageway. Thereafter, one or more supplemental shims are positioned within the passageway so that the supplemental shims and the wear strip are interposed between the circle member and the holder. In this manner, excessive clearance resulting from erosion of the wear strip is accommodated by the supplemental shims.
Although the top-adjust wear assembly of the '353 patent may offer reduced time and labor associated with maintenance of the wear strip, the assembly may still be less than optimal. In particular, the assembly still requires the wear strip to be serviced manually on a regular basis. This manual service results in lost productivity and an operational cost of the machine.
The drawbar-circle-moldboard of the present disclosure addresses one or more of the needs set forth above and/or other problems of the prior art.